The broad objective of this research is to understand and alleviate or control the aggregation of dexoy sickle-cell hemoglobin by conducting quantitative studies of the dependence of this aggregation on such environmental parameters as temperature, concentration, the presence of certain allosteric effectors such as inositol hexaphosphate, and the presence in mixtures of other hemoglobins. The primary aim is to describe these dependences on a quantitative scale instead of just their effect on a minimum gelling concentration. With a background of previous succeses with the use of stability, delay times before the onset of viscosity increase, changes in rotatory diffusion constants and very detailed thermodynamic studies of solubility, we now plan to focus on the crystallization behavior of HboS in mixtures with other human hemoglobins which are either T or R conformers. In this work, which has already been begun, we will continue to rely on measurements of crystal solubility, differential solubility, low-shear viscosity, and electrical birefringence relaxation. In addition we will commence work a little closer to clinical application by reversibly manipulating the mixture ratios of dexoyhemoglobin S to its methemoglobin form in intact human erythrocytes.